What is the minimum amount of roof vents needed for a minimal cabin ? After the last ten years of hauling creek water and outhouse use, I hope to have some basic plumbing by this winter. So cabin will have one (1) toilet, one (1) shower, and two (2) sinks. The sinks will be back-to-back, and kitchen and bathroom will share a common plumbing wall. The Question: Can I get by with only "ONE" (1) Roof Vent for everything.......? And should the Vent be as straight above the toilet as possible.....? Thank you for the help.